Why Your AI-Built App Breaks on Deploy with Supabase Permission Errors

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Apps built with AI tools like Lovable, Bolt, or Cursor often work in preview but fail after deployment due to a Supabase 'permission denied' (error 42501) issue. The root cause is that Row Level Security (RLS) is correctly enabled on the database, but the deployed app sends requests without attaching the logged-in user's identity, causing auth.uid() to return null and RLS checks to block access. Developers are advised to use a request-scoped server client that reads the auth cookie, refresh sessions via middleware, and ensure production domains are listed in Supabase Auth redirect settings. Common shortcuts like disabling RLS or exposing the service role key in client code are strongly discouraged, as they can expose the entire database to unauthorized access. A proper fix involves confirming environment variables, verifying authentication on server routes, and testing the full login-and-load flow on the live URL.

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